The Australasian tektite impact
Glass scattered over a tenth of the globe, from a crater no one has found for certain.
Key facts
- When
- about 790,000 years ago
- Where
- Probably Indochina, perhaps southern Laos
- What hit
- an asteroid probably 1 to 2 km across
- Era
- In the age of humans
- Location
- 15.00° N, 106.50° E
Probably tens of thousands to hundreds of thousands of megatons of TNT.
Perhaps comparable to the Ries impact.
What happened
Across south-east Asia, Australia and the surrounding oceans, people find pieces of black natural glass called tektites. They are melted surface rock, thrown out of a crater and cooled in flight. The Australasian strewn field is the largest and youngest known, covering perhaps a tenth of Earth's surface, from southern China to Australia and even Antarctica.
The glass is all the same age, about 790,000 years, and gets thicker and more abundant towards Indochina, so the crater should be there. Yet a crater that should be about 15 km or more across has proved remarkably hard to find. In 2020 researchers proposed that it lies buried beneath the younger lava flows of the Bolaven Plateau in southern Laos. That idea is promising but not yet confirmed.
Effects
The impact happened while early humans, Homo erectus, lived in the region, so people may have witnessed it, though no sure evidence of that has been found. Some Australian tektites, called australites, flew so far and so fast that they re-entered the atmosphere and were melted again into button and flanged shapes.
The evidence
Millions of tektites, layers of microtektites in deep-sea cores, a few sites with shocked minerals in Indochina, and the geophysical survey of the Bolaven Plateau.
Did you know?
Aboriginal Australians collected australites and used some as tools and in ceremonies long before scientists studied them.
Tektites contain almost no water, which helped prove they formed at very high temperatures.
Related pages
How is impact energy measured? See energy explained, or try the impact calculator.